Retread mold construction



NOV. 24, 1953 E W HAWK|N5ON 2,659,933

RETREAD MOLD CONSTRUCTIO N Nov. 24, 1953 E, W, HAWKlNSoN 2,659,933

RETREAD MOLD CONSTRUCTION Filed Dec. 24, 1952 2 Sheets-Sheet 2 IN VENTOR.

i214@ WMZ/mx@ Patented Nov. 24, 1953 RETREAD MOLD CONSTRUCTION vEarle W.Hawkinson, Minneapolis, Minn., assignor to Paul E. Hawkinson Company,Minneapolis, Minn., a corporation of Minnesota Application December 24,1952, Serial No. 327,809

Z Claims.

My invention relates to improvements in pneumatic tire retreadingapparatus, and more particularly to improvements in tire retreadingmatrices of the type disclosed and claimed in Patents 1,917,262 and2,331,680, and known commercially as Hawkinson treading equipment.

`Still more specifically, my invention relates to improvements inHawkinson sheet metal molds or matrices for applying new tread to earthmover or large size truck tires. In such matrices, the primary steamheating coil is essentially confined to the outer peripheral surface ofthe annular Sheet metal matrix. As a consequence, too frequentlyinsufiicient heat is brought to bear upon the thick sides of the tread,particularly where'it feathers off in contact with the side buffed edgeof the worn tread.

The primary object of my invention is the provision of a mold of theclass above described which is provided with-means for applying heat tothe confining flanges of the matrix independently of the primary sourceof the heat secured to the outer peripheral surface thereof.

A still further object of my invention is the provision of a mold of thetype immediately above described in which the confining fiangeshave-adhered thereto independent tubular heating elements whichterminate on opposite sides of the mold in inlet and outlet terminalswhich may be quickly connected to and disconnected from a source ofsteam or other fluid heating medium.

A still further obj ect of my invention is the provision of a novelmeans for connecting the two independent heating elements, on oppositeconfining fianges, in series.

A still further object of my invention is the provision of novel meanswhereby vulcanizing ternperatures may be readily applied to theconfining flangesor alternatively, in which a cooling fluid may becirculated through the tubular conduit associated with each of theconfining flanges so as to prevent overheating of the sides of the treadfrom the primary heating source-should this be necessary or desirable.

The above and still further objects of myinvention will become apparentfrom the following detailed specification, appended claims and attacheddrawings.

Referring to the drawings, wherein like characters indicate like partsthroughout the several views:

Fig. l is a view partly in front elevation and partly in vertical axialsection, some parts being broken away;

Fig. 2 is a view in top plan, on a reduced scale; and

Fig. 3 is a View in side elevation on the 'same scale as Fig. 2.

Referring with greater particularity to the v drawings, the numeral Iindicates in its entirety a cylinder like matrix formed from sheet metalvide radially inwardly projecting endless V- shaped confining flanges 2.The radially inwardly diverging inner Walls of the V-shaped confiningflanges 2 are identified by the numeral 3, whereas the radially inwardlyconverging outer Walls thereof are identified by the numeral 4. Toeffectively extend the confining fianges 2 beyond the point where theywould normally be weakened by the depth of the V formed thereby, I`secure by welding or the like, as indicated by the numeral 5,cross-sectionally rectangular metallic rings 6. It will be noted thatrings 6 have their inner surfaces 1 lying in the same plane as the innerwalls 3 of the V-shaped confining anges 2 so as to form generallyradially inward extensions of the walls 3. Suitable tread design formingcups 8 are secured to the interior surface 9 of the matrix I by anysuitable means such as welding, screws or the like.

As shown, the matrix I has an endless reinforc ing jacket I0 tightlysecured thereabout with the opposite side edges thereof crimped over theliplike opposite side edge portions I I thereof, as indicated at I2.This structure and the method of forming same is more fully explained inPatents 2,331,679 and 2,339,696. Immediately overlying the crimpedportions I2 and projecting radially outwardly from the outer surface ofthe reinforcing jacket I0 are endless circumferential rails I3 whichfacilitate rotation of the matrix I without causing damage to thespirally wound primary heating coil I4 secured to the outer peripheralsurface of the jacket I ll, such as by solder or the like. Alsopreferably and as shown, a plurality of reinforcing bands I5 tightlyencompass the outer peripheral surface of the jacket I0 inbetween eachconvolution of the heating coil I4. The opposite end portions of theheating coil I4 terminate in enlarged inlet and outlet heads I6 havinglaterally outward projecting openings I1 therein.

It will be noted that the radially inwardly diverging extension rings 6and the inwardly converging walls 4 of the V-shaped confining flanges 2form cross-sectionally V-shaped annular nests I8. Received within thenests I8 is substantially one convolution of tubular heating elements I9which, preferably and as shown, have a radially outer convolution 20secured to the surface 4 of the confining anges 2. The inner and outer 3ends 2| and 22, respectively, of the tubular conduits |9-20 terminate inenlarged heads 23 and 24, respectively, axially outwardly from whichproject suitable connector plugs 25, preferably of the type commerciallyknown as Foster plugs. Either of,theconnector. plugs 25 may be used for,connectiony toi: a: steam pipe 26 having' ably and as shown, steam isconductedaway from,

the matrix l by means of a lead-ofi 3U connected to the oppostie head 23from which the inltpipe 26 is connected. The lead-of pipe 30 is alsopreferably providedY with. aquick acting connector such as a Fosterplug.

WithA the above arrangement anumber of novel results are achievable.For. instance, under circumstanceszwhere' itis felt that. insufcientheat isbeing transferred fromthefprimary heating coil Mito the radiallyinwardly. projected ends'of theV-shaped confining flanges 2 and theextensionss; an independentv source of heat, through conduit .2 6, maybe'snappedon to the connector 25 projecting outwardly'fromeone of theopposed heads 23, the fiexibley conduits 28. snapped on to the'opposedconnectors-25 associated with the opposed heads 24, and the lead-offpipev 30 snapped on. tothe-.connector 25 associated with thevoppositehead 23..- Under some conditions it.,

may be further desirable. to-allow heat to run throughthezcoilsI9-2I-for the same period of time that heatis circulatedthrough.primary coillI4. On the other hand, .the desired curing. period on the sides' of the.treadlmay be considerbly less than that required. by theprimaryheatingcoil HL.I Itv mayI even be. that it is further desirable tok run.cooling fluidthrough the pipes V2 6,' .2 8,A and course, maybe readily.done bysubstituting cold water for. the steam in said conduits.

While-Ihave shown acommercial embodiment of..my invention,` it 4shouldbe obvious thatsame is capable of modificationwithout departure' from Inorder to connect the two'.

As shown, the conduit 28,0Verliesthe the scope of the invention asdefined by the appended claims.

What I claim is:

1. A tire retreading device comprising an integral cylinder-like matrixformed from sheet metal and having radially inwardly projecting endlesstreafd material confining flanges adjacent its opposite side edges, atubular heating element coiled about the outer peripheral surface ofsaid matrix and terminating in inlet and outlet heads adjacent oppositeside edges, a circular tubular heating element wound about and adheredto the axially; outer side of: each of said confining fiangesVeachpfsaidlast mentioned heating elements` terminating in laterally outwardlyprojectingttings, and a, flexible conduit spanning the radially outersurface of said matrix and provided at its opposite ends with couplerseach adapted to be detachably secured to one of the fittings associatedwith each of said last-mentioned heatingelements.

2. Thestructure defined in claim 1 in furthe combination with radiallyoutwardly projectingy endless rail elements secured to the outer surfaceof the matrix one each adjacent an opposite side edge thereof, said railelements having greater radial heights than the iirst-mentioned tubularheating element, and in which said con,-

ning flanges are formed from sheet metal bent in generallycross-sectionally V-shape and are provided with extension elementscomprisingA EARLE W. HAWKINSO-N.

References Citedin the fileof this patent UNITED STATES PATENTS NumberName Date 2,651,078 Hawkinson Sept. 8, 1953 FOREIGN PATENTSy NumberCountry Date 13,406/23 Australia July' 14,' 1924

